It was the moment when two egos collided. She was the party apparatchik who wanted to stamp her authority on Whitehall in her role as special adviser to the Secretary of State for Transport, Stephen Byers. He was the tough BBC Moscow veteran determined to maintain his position as head of communications at the Department of Transport.
Even among the party spin doctors, Jo Moore was a special case. "She was a political adviser with a difference. She wanted her hands on every announcement," said one insider. She began her career at Labour's former Walworth Road headquarters as a lowly press officer when Labour was toiling against a hostile media, and Peter Mandelson was in charge. During the 1997 general election campaign, she was ever-present, clipboard in hand, working in Alastair Campbell's shadow. She was sharp, trusted and totally committed to the party. After departing for two years with the lobbyists Westminster Strategy, she returned to the Labour fold, working for Stephen Byers at the DTI.
There were rumours of clashes with civil servants, which grew when she moved with Byers to Transport. It was there that she made her greatest error, e-mailing colleagues on 11 September that the terrorist attacks made it a "good day to bury bad news". She apologised, but there were still questions about her judgement.
Mr Sixsmith's career should have prepared him for the realpolitik of the department. As BBC correspondent in Moscow, he was used to dealing with the party apparatchiks and keeping his own line on the news. He had a reputation for being wilfully focused.
When he returned to London in the mid-1990s he moved from journalism to being head of communications under Harriet Harman at the Department of Social Security. The job was surreal, for Harman had fallen out with her junior minister, Frank Field. Sixsmith spent much of his time pretending to the media that their relationship was harmonious, while trying to get the two of them to say as little as possible.
Although he was taken aback by the bitterness of New Labour's infighting and the blurred lines between special advisers and civil servants (and quit to work in the private sector), ambition brought him back. He joined Transport just days before Ms Moore wrote her memo. The next five months must have made Moscow and the DSS seem idyllic. His turf war with Ms Moore was too damaging for it to continue. They both had to go.Reuse content